Colin Kaepernick celebrates Nevada's 52-31 pasting of Cal in 2010, when Kaepernick threw for two TDs and ran for three.

Photo: Lance Iversen, The Chronicle

Colin Kaepernick celebrates Nevada's 52-31 pasting of Cal in 2010,...

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Nevada's Colin Kaepernick runs into the end zone for his second touchdown in the first half of their NCAA college football game Friday, Sept. 17, 2010,against California in Reno, Nevada. Nevada leads at the half 24-14

All it took to convince the rookie NFL coach that Colin Kaepernick just might be the 49ers' quarterback of the future was a little game of catch. Or burnout.

It happened in the spring of 2011, between the NFL scouting combine and the draft. Harbaugh and general manager Trent Baalke road-tripped to Reno to check out this Kaepernick kid. They hadn't met him at the combine and Harbaugh was very curious.

Many experts were super-cool on Kaepernick as an NFL prospect, but Harbaugh had heard a few reports that sounded almost like Bigfoot sightings, and he was intrigued.

Harbaugh's interest in Kaepernick started at least a year earlier.

Before Kaepernick's senior year at Nevada he wrangled an invitation to the Manning Passing Academy near New Orleans. The top college quarterbacks are invited and courted by the Mannings (Archie, Peyton and Eli), who roll out the red carpet. Ostensibly, the college hotshots come as "counselors" for the high school kids, but it's really an NFL showcase for the big guns. Andrew Luck and Terrelle Pryor were headliners that summer.

Kaepernick had to beg his way in. He had to apply and then have Nevada coach Chris Ault write a letter of recommendation.

According to one post-camp blog post on CBSSports.com, "Kaepernick surprised some with his velocity. ... Kaepernick is well known for his (college) production ... but is viewed by many scouts as a product of Chris Ault's 'pistol' offense."

If the scouts weren't impressed, Luck apparently was. He and Kaepernick became pals, and when Luck returned to Stanford, Harbaugh asked him if he'd seen anyone who looked good.

Oh yeah, Luck said. Colin Kaepernick.

Andrew Luck: the Bay Area gift that keeps on giving.

In picking Luck's brain, was Harbaugh thinking and plotting ahead one year, to when he might be an NFL coach for a team in need of a good young quarterback? Who knows?

Fast forward to the following spring. Harbaugh gets the 49ers' job, decides Alex Smith will be his quarterback for the present, but what about the future?

That's when Harbaugh and Baalke head to Reno.

Harbaugh's M.O. is uber-enthusiasm. Whether he's meeting a blue-chip prep recruit or a potential 49ers' draftee, Harbaugh doesn't do tea and crumpets. He wants to skip the chit-chat and get dirty.

He's been known to drag a high school kid from his living room and out to the driveway hoop for a spirited game of one-on-one.

Harbaugh and Kaepernick talked for a while, but Harbaugh wanted to see the skinny kid throw, so they hit the field.

After Kaepernick tossed some passes to Baalke, running routes, Harbaugh threw down the gauntlet.

"I think the first thing that came to mind was, well, number one, the energy he brought," Kaepernick said later, recalling their first meeting. "He was running all over the field with me, throwing the football around. From the get-go it was just a competition out there, we're going to see who can throw the most perfect spirals to each other. And then we're going to see who can be the most accurate throwing through the goalposts from different spots."

If you think either man was casual about the little games they were playing, you don't know them.

Harbaugh never plays a game to lose. His over-the-top competitiveness in pick-up basketball games is legendary. For him, there is only one level of competition.

Same with Kaepernick, who was known in high school, seriously, as a hellacious competitor in lunchtime four-square games.

They went at it.

Asked later about their playdate, Harbaugh said that once he got out there, he was just having fun tossing the old rock around, and that Kaepernick seemed to be in the same spirit.

What's more likely is that Harbaugh - who had already watched a ton of video on Kaepernick, and knew well his college stats and exploits, and knew that many experts were cool on Kaepernick, considering him a small-time, gimmick-offense stat monster - was intrigued and was ready to push all the scouting bull corn aside and make his own judgment.

There's no way Kaepernick treated the tryout casually. He knew every throw that day might determine whether he'd ever get a legitimate shot at his dream, a chance to play quarterback in the NFL.

After their friendly duel to the death, Harbaugh briefly thanked Kaepernick, jumped into the car with Baalke, and sped away. Harbaugh sometimes dispenses with flowery social graces (ditto Baalke).

A friend asked Kaepernick how the meeting with Harbaugh went.

"I think I pissed him off," Kaepernick said.

Maybe he did. Maybe that's why Harbaugh decided this was the guy for the 49ers.